1. Newborns exposed to methadone prenatally had worse neurobehavior scores than those who were not.
2. Infants belonging to one of four particular neurobehavioral profiles were associated with poorer cognitive and neuromotor outcomes at 24 months.
Evidence Rating Level: 2 (Good)
As the opioid crisis continues to take its toll in North America, many pregnant mothers are using opioid agonist therapy, such as methadone and buprenorphine, as safer, controlled prescription alternatives. Infants whose mothers used methadone treatment during pregnancy are known to exhibit differences in the Neonatal Intensive Care Unit Network Neurobehavioral Scale (NNNS). The long term effects on neurodevelopment of the infant is far more limited due to poorer quality or smaller studies. This study used data from the prospective, longitudinal Christchurch Methadone In Pregnancy (MIP) Study and had two aims. One was to compare neurobehaviors in infants exposed prenatally to methadone (n=86) to those who were not (n=103) and the other was to identify a specific neurobehavioral profile that was linked to worse neurodevelopmental outcomes at 2 years of age. Using NNNS summary scores, infants exposed to methadone prenatally had poorer attention, regulation, and quality of movement, increased excitability, arousability, expression of non-optimal reflexes, hypertonicity, and total signs of stress abstinence, including those of central nervous system, visual, genitourinary, and state. From this group of subjects, four unique neurobehavioral profiles were created. One profile, Profile 4, had poorer attention scores than most of the other profiles, required the most handling, had the lowest scores on self-regulation and the highest on arousal, excitability, hypertonicity, non-optimal and asymmetric reflexes, and exhibited the highest stress abstinence and poorest quality of movement. Infants of this profile had the poorest NSSS score and were more likely to be born to mothers on welfare with more pregnancies and terminations, to be male, to be born preterm and smaller at birth, to spend more than 2 weeks in a special care baby unit and more than 2 weeks in hospital postnatally, and to be more likely to need pharmacological treatment for neonatal abstinence syndrome. Children of this profile had the worst clinical outcomes at 24 months assessed by BSD-II, MDI and PDI, scales of child cognitive and neuromotor function, respectively. This study confirmed the findings of previous studies that exposure to methadone prenatally can significantly affect neurobehaviors at birth compared to unexposed infants. Furthermore, infants belonging to the certain neurobehavior profile 4 (13% of infants) had the worst outcomes of all methadone-exposed individuals at 24 months. These findings can help identify infants who may be at increased risk of worse neurodevelopment compared to others exposed to methadone prenatally.
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